Fire alarm



Nov. 15, 1938. A. HELME'RSE'N FIRE ALARM Original Filed May 25, 1935 5 Sheets-Sheet l Ifiuenfm flda Zf 51792272 6715672,

Attm'ney Nov. 15, 1938. A HELMERSEN 2,136,740

' FIRE ALARM 7 Original Filed May 25, 1955 s Sheets-Sheet 2 5a 2a /za lllllllllll e /7 I nventqr flmaorizn Attorney Nov. 15, 1938. A. K. HELMERSEN FIRE ALARM Original Filed May 25, 1955 3 Sheets-Sheet 3 Inventor fldaif/ff/dwman,

Attomey Patented Nov. 15, 1938 UNITED STATES PATENT OFFICE FIRE ALARM 23,491, May 25, 1935.

This application Decemher 7, 1937, Serial No. 178,603

4 Claims.

This is a substitute application for applicant's abandoned application, Ser. No. 23,491, filed May 25, 1935.

This invention relates to an alarm device and more particularly to a device of this character especially adapted to be set into operation when the heat of the room or the like is caused to rise, as for example, because of fire, above a predetermined temperature for sounding an electrically operable signal device.

The invention together with its objects and advantages will be best understood from a study of the following description taken in connection with the accompanying drawings wherein:

Figure 1 is a wire diagram.

Figure 2 is a side elevational view of a thermal element embodying the features of the present invention.

Figure 3 is an end elevational View of the thermal element.

Figure 4 is a fragmentary sectional view showing the mounting for a rocker arm.

Figure 5 is a plan view of a spring.

Figure 6 is a sectional view through the thermal element.

Figure 7 is an end elevational view of the thermal element with certain parts removed.

Figure 8 is a plan view of the rocker arm.

In accordance with the present invention the alarm consists broadly of a thermal element indicated generally by the reference numeral I0 and wired in circuit as shown in Figure l with a transformer I I and an electrically operable signal element in the present instance a bell I2. It will 35 thus be seen that in response to a rise in temperature beyond a predetermined degree, the thermal element I0 will operate to close a switch indicated generally by the reference numeral I3 that is also arranged in the aforementioned circuit for 40 closing said circuit through the signal I2 for sounding the latter.

The improved thermal element I0 comprises a sealed casing I4 of suitable material in which is confined a suitable liquid I5. The casing I4 is substantially oval in end elevation and in the end thereof is formed for the reception of plates I6 of insulating material as best shown in Figure 6. These plates I6 have depending end portions I6a forming legs for supporting the receptacle I4 50 above a supporting surface as also clearly suggested in Figure 2.

A substantially U-shaped bar I! of conductive material has the ends thereof secured to the plates I6 through the medium of an elongated bolt I8 that also serves as a binding post. The

bolt I8 extends through the casing I4 and is encased within a tube I9 of metal extending between the end walls of the case I4 and lined with insulating material 20 as also shown in Figure 6. On the threaded end of the bolt I8 is a binding nut 2|.

The container [4 is of conductive material and is provided at one end with a binding post 22 as shown in Figure 1. Also, on the top thereof the sealed container I4 is provided with a fixed contact 23 provided for the switch I3. The movable contact of the switch is indicated by the reference numeral 24 and is provided on one end of a rocker arm 25. The contact 24 operates through a suitable opening 26 provided therefore in the member ll.

The rocker arm 25 has a reduced portion pivoted as at 25c between the upstandnig arms of a bifurcated post 28 that is formed with an integral pin 29 anchored within a suitable opening provided therefore, in the member IT. The pin 29 also extends through an opening in one end of a spring 30 for anchoring this spring, the latter being curved as shown in Figure 6 and engaging the fork end of the arm 25 as shown.

Threaded into the member I! is a post 3| on which is threaded the hub of a suitably graduated dial 32 secured at the desired adjustment through the medium of a lock nut 33. The hub of the dial 32 is provided with a shoulder against which the heads 34 provided on the arms of the fork end 21 of arm 25 engage, which end of the arm straddles the hub of the dial 32 in a manner clearly suggested in Figure 2. It will thus be seen that by adjusting the dial 32 axially of the post 3| contact 24 may be placed in the desired spaced relation to the contact 23 so that the contact 23 will engage the contact 24 for completing the circuit only after a predetermined temperature has been exceeded.

As is obvious, and as shown in Figure l the binding posts I8 and 22 are provided for connecting the wires of the circuit to the device I0 for so arranging said device and switch I3 in the circuit that a closing of the switch I3 will complete the circuit to the bell I2 for setting the latter in operation.

As thought to be apparent the switch I3 is adjusted so as to be closed at a predetermined temperature by properly adjusting the dial 32 axially of its post 3|. When the temperature rises above a predetermined amount the casing I4 will be so effected by the heat as to expand suiiiciently to engage contact 23 with contact 24 for closing the circuit and thereby sounding the signal l2.

It will be understood that the apparatus may be used either with a battery circuit or with the usual house circuit.

Having thus described the invention, what is claimed as new is:

1. In a device of the character described, an elongated expansible container of conductive material and of oval shape in cross section and having a peripheral wall and end walls spaced inwardly from the respective opposite ends of the peripheral wall together with an insulated tube ext-ending between said end walls centrally of the container, supporting plates of insulating material for said container and having portions fitting within the ends of the peripheral wall of said container, a substantially U-shaped member having legs bearing against and spaced from the ends the container by said plates, said legs and ates being provided with openings alining with ne another and with said tube, a bolt extending rough the openings and said tube for securing p-ed member to the container, said d to serve as a binding post, a contact mounted on the peripheral wall of said ng, and a contact member mounted on said e ,ped member and adapted to be engaged by the first named contact upon an expansion of id casing, and a volatile liquid confined i said casing for expanding the latter when voted to excessive heat.

a. In a thermal electric alarm, the combina- 01" a thermic shell of oval shape in cross section and having a binding post extending therethrough and insulated therefrom, a substantially Ushaped member receiving between the legs thereof said shell and having openings in the legs thereof for receiving said post whereby said shell and U-shaped member are secured in assembled relation, insulation plates spacing the legs of he U-shaped member from the shell, a contact member on one of the wider sides of said shell, a post rising from said U-shaped memher at the closed end of the U, a rocker arm pivotally mounted on said post and having a conon one end thereof operating through an ng in the closed end of the U-shaped memocr and in substantial alinement with the first named contact for cooperation therewith to complete a circuit, a spring anchored to the U shaped member by said post and having an end bearing against the rocker arm to rotate the same in one direction, and means mounted on said U- shaped member and engageable with said rocker arm for adjusting the latter in opposition to said spring.

3. In a thermal electric alarm, the combination of a thermic shell of oval shape in cross section and having a binding post extending therethrough and insulated therefrom, a substantially U-shaped member receiving between the legs thereof said shell and having openings in the legs thereof for receiving said post whereby said shell and U-shaped member are secured in assembled relation, insulation plates spacing the legs of the U-shaped member from the shell, a contact member on one of the wider sides of said shell, a post rising from said U-shaped member at the closed end of the U, a rocker arm pivotally mounted on said post and having a contact on one end thereof operating through an opening in the closed end of the U-shaped member and in substantial alinement with the first named contact for cooperation therewith to complete a circuit, a spring anchored to the U-shaped member by said post and having an end bearing against the rocker arm to rotate the same in one direction, means mounted on said U-shaped member s and engageable with said rocker arm for adjusting the latter in opposition to said spring, and said means including a threaded post ex tending from the closed end of the U-shaped member, a dial having a hub threadedly engaged with the last named post, and said hub having a shoulder engaging the end of the rocker arm remote from the contact carried by said rocker arm for limiting rocking movement of said arm in one direction.

4. In a device of the character described, a thermic shell of oval shape in cross section and having a contact on one of its wider sides, a contact and indicator assembly arranged in the path of the first named contact, and means for mounting said combined contact and indicator assembly on said shell including a substantially U- shaped member between the legs of which said shell is disposed. insulation plates spacing the legs from the ends of the shell, and an elongated binding post extending through the legs of the U-shaped member and said shell for securing the U-shaped member to the shell, said shell having arranged internally therein, a longitudinally extending tube, and a sleeve of insulat ing material lining said tube and within which the binding post is positioned.

ADOLF K. HELMERSEN. 

